Dimensional changes occur between structural members in response to expansion and contraction due to, for example, temperature changes, shortening and creep caused by pre-stressing concrete members, seismic cycling, vibrations, deflections caused by live loads, and longitudinal forces caused by wind loads, and vehicular traffic. A gap is purposefully provided between the adjacent structural members for accommodating the dimension changes. These dimensional changes result in the expansion and contraction of the width of the gap between the spaced apart structural members. Expansion joint systems are positioned within the gap to accommodate the movements in the vicinity of the gap, but still permit flow of traffic across the gap.
Finger joint expansion joint systems are one type of expansion joint system that is utilized in bridge and roadway expansion joint applications. Finger joint expansion joint systems utilize plates in the form of elongated fingers which bridge the gap between spaced apart structural members. The fingers of the plates connected to one structural member are interdigitated with the fingers of the finger plate connected to the opposing structural member to provide a consistent surface to allow traffic to traverse the gap.
Finger joints provide for longitudinal movement across the expansion joint gap in the relative directive of traffic. While finger joint systems are preferred in certain jurisdictions, conventional finger joint systems are not capable of accommodating transverse movement (ie, movement in a direction that is perpendicular or substantially perpendicular to the longitudinal direction of traffic across the expansion joint gap) within the expansion joint gap.
Transverse movement must be accommodated in many expansion joint system designs, such as those which experience seismic cycling or seismic events. What is needed in the expansion joint industry is an improved finger joint expansion joint system that is capable of accommodating both longitudinal and transverse movement occurring within the vicinity of the expansion joint gap.